# Render Converter Converter Source
# a bidirectional connection
+
+def cached(f):
+ name = f.__name__
+ def wrapper(self):
+ if self.cache is None:
+ return f(self)
+ if name not in self.cache:
+ self.cache[name] = (True, f(self))
+ return self.cache[name][1]
+ return wrapper
+
class Element(object):
CHANGED_DEFAULT = 0 # initial "pull" state
CHANGED_ALL = 1 # really everything changed
self.master = None
self.source = None
self.__suspended = True
- self.clearCache()
+ self.cache = None
def connectDownstream(self, downstream):
self.downstream_elements.append(downstream)
# we should not disconnect from upstream if
# there are still elements depending on us.
assert len(self.downstream_elements) == 0, "there are still downstream elements left"
-
+
# Sources don't have a source themselves. don't do anything here.
if self.source is not None:
self.source.disconnectDownstream(self)
-
+ # sources are owned by the Screen, so don't destroy them here.
+ self.destroy()
+
def disconnectDownstream(self, downstream):
self.downstream_elements.remove(downstream)
if self.master == downstream:
# default action: push downstream
def changed(self, *args, **kwargs):
- self.clearCache()
+ self.cache = { }
self.downstream_elements.changed(*args, **kwargs)
- self.clearCache()
+ self.cache = None
def reconnectUpstream(self, new_upstream):
assert self.source is not None
self.source = new_upstream
- def clearCache(self):
- self.cache = None
-
def setSuspend(self, suspended):
changed = self.__suspended != suspended
if not self.__suspended and suspended:
def doSuspend(self, suspend):
pass
+
+ def destroy(self):
+ pass